The invention relates to a rotational position detector for detecting a rotational angle and a rotational reference position of a rotary shaft used, for example, in an internal combustion engine.
In a known rotational position detector for an internal combustion engine, for example, a disc rotating in synchronism with the rotation of the internal combustion engine is provided with teeth-like projections equiangularly disposed. A couple of sensors are used; one for sensing the projections and the other for sensing a reference position. This type of rotational position detector, however, is costly because of the use of two sensors, and suffers from a position error in the sensed signal because of the distance error between the two sensors.